Formic Acid, a Ubiquitous but Overlooked Component of the Early Earth Atmosphere

Prebiotic Synthesis of 3',5'-Cyclic Adenosine and Guanosine Monophosphates through Carbodiimide-Assisted Cyclization

3',5'-Cyclic nucleotides play a fundamental role in modern biochemical processes and have been suggested to have played a central role at the origin of terrestrial life. In this work, we suggest that a formamide-based systems chemistry might account for their availability on the early Earth. In particular, we demonstrate that in a liquid formamide environment at elevated temperatures 3',5'-cyclic nucleotides are obtained in good yield and selectivity upon intramolecular cyclization of 5'-phosphorylated nucleosides in the presence of carbodiimides.

The Nature of the Spark Is a Pivotal Element in the Design of a Miller-Urey Experiment

Miller and Urey applied electric sparks to a reducive mixture of CH4, NH3, and water to obtain a complex organic mixture including biomolecules. In this study, we examined the impact of temperature, initial pressure, ammonia concentration, and the spark generator on the chemical profile of a Miller-Urey-type prebiotic broth. We analyzed the broth composition using Gas Chromatography combined with Mass Spectroscopy (GC/MS). The results point towards strong compositional changes with the nature of the spark. Ammonia exhibited catalytic properties even with non-nitrogen-containing compounds. A more elevated temperature led to a higher variety of substances. We conclude that to reproduce such a broth as well as possible, all the studied parameters need to be tightly controlled, the most difficult and important being spark generation.

Synthesis of prebiotic organics from CO2 by catalysis with meteoritic and volcanic particles

The emergence of prebiotic organics was a mandatory step toward the origin of life. The significance of the exogenous delivery versus the in-situ synthesis from atmospheric gases is still under debate. We experimentally demonstrate that iron-rich meteoritic and volcanic particles activate and catalyse the fixation of CO₂, yielding the key precursors of life-building blocks. This catalysis is robust and produces selectively aldehydes, alcohols, and hydrocarbons, independent of the redox state of the environment. It is facilitated by common minerals and tolerates a broad range of the early planetary conditions (150-300 °C, ≲ 10-50 bar, wet or dry climate). We find that up to 6 × 10⁸ kg/year of prebiotic organics could have been synthesized by this planetary-scale process from the atmospheric CO₂ on Hadean Earth.

A Computational Quantum-Based Perspective on the Molecular Origins of Life’s Building Blocks

The search for the chemical origins of life represents a long-standing and continuously debated enigma. Despite its exceptional complexity, in the last decades the field has experienced a revival, also owing to the exponential growth of the computing power allowing for efficiently simulating the behavior of matter—including its quantum nature—under disparate conditions found, e.g., on the primordial Earth and on Earth-like planetary systems (i.e., exoplanets). In this minireview, we focus on some advanced computational methods capable of efficiently solving the Schro¨dinger equation at different levels of approximation (i.e., density functional theory)—such as ab initio molecular dynamics—and which are capable to realistically simulate the behavior of matter under the action of energy sources available in prebiotic contexts. In addition, recently developed metadynamics methods coupled with first-principles simulations are here reviewed and exploited to answer to old enigmas and to propose novel scenarios in the exponentially growing research field embedding the study of the chemical origins of life.

Computational Analysis of a Prebiotic Amino Acid Synthesis with Reference to Extant Codon-Amino Acid Relationships

Novel density functional theory calculations are presented regarding a mechanism for prebiotic amino acid synthesis from alpha-keto acids that was suggested to happen via catalysis by dinucleotide species. Our results were analysed with comparison to the original hypothesis (Copley et al., PNAS, 2005, 102, 4442–4447). It was shown that the keto acid–dinucleotide hypothesis for possible prebiotic amino acid synthesis was plausible based on an initial computational analysis, and details of the structures for the intermediates and transition states showed that there was wide scope for interactions between the keto acid and dinucleotide moieties that could affect the free energy profiles and lead to the required proto-metabolic selectivity.

Aminomalononitrile inspired prebiotic chemistry as a novel multicomponent tool for the synthesis of imidazole and purine derivatives with anti-influenza A virus activity

Amino imidazole carbonitrile derivatives decorated with α-amino acid side-chains have been synthesized by a multicomponent microwave assisted reaction inspired by the prebiotic chemistry of aminomalononitrile as a tool for generating high chemical diversity. These compounds were used as annulation synthons for the preparation of 8,9-disubstituted-6,9-dihydro-1H-purin-6-ones by reaction with formic acid as a simple C-1 donor reagent. The novel heterocycles were characterized by significant activity against influenza A virus, amino imidazole carbonitrile derivatives showing the highest activity. Thus, the chemical complexity generated by prebiotic chemistry furnished a general tool for the identification of novel antiviral agents.

Amino imidazole carbonitrile derivatives decorated with α-amino acid side-chains have been synthesized by a multicomponent microwave assisted reaction inspired by the prebiotic chemistry of aminomalononitrile for generating high chemical diversity.

The influence of the environment in chemical reactivity: the HCOOH formation from the H2O + CO reaction

The reaction between carbon monoxide and water was studied occurring in an aerosol medium rich in methanol. This environment is plausible for the primitive and prebiotic Earth atmosphere. The chemical environment is expressed in terms of dielectric constant (ε) and the chemical system was modeled employing the polarizable continuum model (PCM). The main results were acquired from calculations employing the M06-2X density functional for the electronic structure calculations and the canonical variational theory with small curvature tunneling for the chemical kinetic calculations. The rise of ε affects both the thermochemistry and the kinetics of the reaction, increasing the barrier height and decreasing the rate constant for the reaction occurring at room temperature. For example, the rate constant at 300 K is 5-10× 10^- 53 cm³ ⋅molecule^- 1 ⋅s^- 1 for low dielectric constant (ε < 3) and around 2-4× 10^- 53 cm³ ⋅molecule^- 1 ⋅s^- 1 for ε between 7 and 40. Our results indicate that the ε variation allows a fine tuning to the rate of the reaction.

Prebiotic Organic Chemistry of Formamide and the Origin of Life in Planetary Conditions: What We Know and What Is the Future

The goal of prebiotic chemistry is the depiction of molecular evolution events preceding the emergence of life on Earth or elsewhere in the cosmos. Plausible experimental models require geochemical scenarios and robust chemistry. Today we know that the chemical and physical conditions for life to flourish on Earth were at work much earlier than thought, i.e., earlier than 4.4 billion years ago. In recent years, a geochemical model for the first five hundred million years of the history of our planet has been devised that would work as a cradle for life. Serpentinization processes in the Hadean eon affording self-assembled structures and vesicles provides the link between the catalytic properties of the inorganic environment and the impressive chemical potential of formamide to produce complete panels of organic molecules relevant in pre-genetic and pre-metabolic processes. Based on an interdisciplinary approach, we propose basic transformations connecting geochemistry to the chemistry of formamide, and we hint at the possible extension of this perspective to other worlds.

Primordial Radioactivity and Prebiotic Chemical Evolution: Effect of γ Radiation on Formamide-Based Synthesis

Although the effect of ionizing radiation on prebiotic chemistry is often overlooked, primordial natural radioactivity might have been an important source of energy for various chemical transformations. Estimates of the abundances of short-lived radionuclides on early Earth suggest that the primordial intensity of endogenous terrestrial radioactivity was up to 4 × 10³ times higher than it is today. Therefore, we assume that chemical substances in contact with radioactive rocks should therefore undergo radiolysis. The calculations are followed by research investigating the influence of ionizing γ radiation on basic prebiotic substances, including formamide mixed with various clays, which might have played the role of a catalyst and an agent that partially blocked radiation that was potentially destructive for the products. Our explorations of this effect have shown that the irradiation of formamide-clay mixtures at doses of ∼6 kGy produces significant amounts of urea (up to the maximal concentration of approximately 250 mg L^-1), which plays a role in HCN-based prebiotic chemistry.